This fixes various (not all) wrong @covers annotations that
are reported as warnings by PHPUnit when it's run with
code-coverage enabled.
When possible, the preferred solution is to change to
@covers at class level, that is the recommended way.
If multiple classes are involved, then a mix of @coversDefaultClass
and @covers at method level are used (always trying to use the
minimum needed patch).
This is the first of a series of issues created as sub-tasks
of MDL-82142.
ad5fe71868